System and method for controlling the temperature of an open-air area

ABSTRACT

A system for controlling the temperature of an open-air area. The system comprises a boundary wall defining at least a portion of the perimeter of the open-air area to be temperature-controlled, and a floor having a heating or cooling element, wherein the system is effective to control the temperature of the area. The heating or cooling element may include a network of interconnected pipes in the floor, a quantity of fluid disposed within the pipes, a heat exchanger for heating or cooling the fluid, and a pump for circulating the fluid through the pipes. The system may further include a network of interconnected ductwork in the boundary wall, a heating or cooling element for heating and cooling air, a blower for circulating the heated or cooled air through the ductwork, and a plurality of diffusers in the boundary wall to communicate the air to the open-air area.

This application claims priority to U.S. provisional application60/487,779, filed Jul. 16, 2003, the contents of which are herebyincorporated by reference.

FIELD

This invention relates to a system and method for controlling thetemperature of an external area. In particular, this invention relatesto a system and method for controlling the temperature of an open-airvenue, such as a patio.

BACKGROUND

Open-air venues, such as restaurant and coffee shop patios, are popularwith customers who enjoy relaxing outside in the fresh air. In addition,customers seated in an open-air venue are often able to better take inthe atmosphere of the locale, such as people-watching and viewing localscenery and architecture. Open-air seating may also be desirable tocomplement an establishment's decor and/or theme.

In many climates open-air venues are comfortably utilized only a smallportion of the year because seasonable temperature variations result inan outside temperature that is often either too hot or too cold. Priorattempts at extending the utilization of open-air venues includeenclosing the space with a roof and/or side walls, using heating unitssuch as propane or infrared heaters during the winter, and using spotcoolers and/or misters in the summer. Such enclosures andheating/cooling units impede upon the venue's usable space and detractfrom the outdoor experience by their appearance, noise and thenoticeable temperature differential in comparison to the outside airtemperature.

There is a need for an open-air venue that can be heated and cooled asneeded to extend the number of days during which the venue may becomfortably utilized. There is a further need for a climate-controlledoutdoor venue wherein the climate control devices do not detract fromthe atmosphere of the venue.

SUMMARY

A system and method are disclosed for controlling the climate of anoutdoor venue, such as a patio. A foundation serving as a low supportwall encloses and disguises air-moving ductwork and diffusers connectedto heating and/or cooling equipment. A transparent barrier is locatedatop the foundation that provides the venue with an open environmentwhile establishing a climate-control area with a wind break. A floor ofthe venue may also include embedded heating and/or cooling capability.Additional climate-control devices may include movable sun screens toreduce the heat load on the venue during warm weather.

By controlling the environment of the venue in a non-obtrusive way theoutdoor experience is much richer, creating an illusory effect of anopen, yet temperature-controlled area. This is accomplished byconditioning the living space of an area from the floor up, as opposedto ceiling-down, as is generally practiced in the art. As such, thepresent invention focuses on the living space from the floor of thevenue to about six feet in height. This is a key issue when attemptingto condition an outdoor space that has no roof, such that the totalspacial volume is nearly infinite.

An embodiment of the present invention is a system for controlling thetemperature of an open-air area. The system comprises a boundary walldefining at least a portion of the perimeter of the open-air area to betemperature-controlled, a floor, and a heating or cooling element in thefloor, wherein the system is effective to control the temperature of theopen-air area.

Another embodiment of the present invention is a system for controllingthe temperature of an open-air area. The system comprises a boundarywall defining at least a portion of the perimeter of the open-air areato be temperature-controlled, a network of interconnected ductwork inthe boundary wall, a heating or cooling element to heat or cool air, ablower for circulating the heated or cooled air through the ductwork,and a plurality of diffusers in the boundary wall to communicate theheated or cooled air to the open-air area. The system is effective tocontrol the temperature of the area.

Still another embodiment of the present invention is a system forcontrolling the temperature of an open-air area. The system comprises aboundary wall defining at least a portion of the perimeter of theopen-air area to be temperature-controlled, a floor including a networkof interconnected pipes in the floor and a quantity of fluid disposedwithin the pipes, a heat exchanger for heating or cooling the fluid, apump for circulating the fluid through the pipes, a network ofinterconnected ductwork in the boundary wall, a heating or coolingelement to heat or cool air, a blower for circulating the heated orcooled air through the ductwork, and a plurality of diffusers in theboundary wall to communicate the air to the open-air area. The system iseffective to control the temperature of the open-air area.

BRIEF DESCRIPTION OF THE DRAWINGS

Further features of the inventive embodiments will become apparent tothose skilled in the art to which the embodiments relate from readingthe specification and claims with reference to the accompanyingdrawings, in which:

FIG. 1 is a top plan schematic view of the general arrangement of anoutdoor venue according to an embodiment of the present invention;

FIG. 2 is a side elevational view of the general arrangement of aboundary wall according to an embodiment of the present invention;

FIG. 3 is a top plan view of a portion of a network of pipes used withan embedded floor heating/cooling system according to an embodiment ofthe present invention;

FIG. 4 is a schematic diagram of a temperature control system for aheating/cooling system embedded in a floor according to an embodiment ofthe present invention;

FIG. 5 is a schematic diagram of a temperature control system for aheating/cooling system embedded in a foundation of a boundary wallaccording to an embodiment of the present invention;

FIG. 6 is a schematic of a supplemental screen according to anembodiment of the present invention;

FIG. 7A is a view in cross section of the pipes of FIG. 3;

FIG. 7B is a simplified view of the pipes of FIG. 7A; and

FIG. 7C is a view in cross section of pipes installed in a boundary wallaccording to an embodiment of the present invention.

DETAILED DESCRIPTION

A top plan schematic view of the general layout of a system forcontrolling the temperature of an external environment is depicted inFIG. 1. An area to be temperature-controlled, such as a patio 10,comprises a boundary wall 12, a floor 14 and a movable screen 16.Boundary wall 12 defines the perimeter of the area to betemperature-controlled. Boundary wall 12 also serves as a wind break tohelp confine conditioned air temporarily. A floor 14 covers the groundin the area enclosed by boundary wall 12. A movable screen 16 mayoptionally be located proximate the boundary wall 12. Movable screen 16may be adapted to move upon a track 18, or may be adapted to movefreely, such as on wheels (not shown). The perimeter of patio 10 may beat least partially bounded by a partition 20, such as a wall of abuilding. Patio 10 may include at least one access 23 in partition 20and/or boundary wall 12. Access 23 may be, without limitation, an openentry way, a conventional “air door” of vertically-directed air, ascreen door, a solid entry door, and conventional plastic strip doors.

A side elevational view of an example boundary wall 12 is depicted inFIG. 2. In a preferred embodiment boundary wall 12 has a foundation 22and an optically transmissive portion 24. Foundation 22 may beconstructed from any conventional materials, such as stone, brick andconcrete. Foundation 22 is preferably about 18 inches thick and about 3feet high, constructed around the perimeter of patio 10. The thicknessof foundation 22 will be dictated by the materials selected and thestructural requirements for the materials. The thickness of thefoundation 22 will also be influenced by the design of conventionalheating/cooling ductwork and diffusers 26 to be installed within thefoundation, as will be discussed in more detail below. Opticallytransmissive portion 24 is mounted atop foundation 22 and provides patio10 with the sensation of an open atmosphere while providing a windbreak. Optically transmissive portion 24 may be supported in anyconventional manner, such as vertical and/or horizontal frames,structures and braces attached to foundation 22. Optically transmissiveportion 24 may be constructed from any conventional materials, such astempered glass, structural glass, acrylics, and polycarbonates such asLEXAN.

A plan view of a schematic of a portion of floor 14 is shown in FIG. 3.Floor 14 may be constructed of poured concrete having a network ofinterconnected pipes 30 in the floor. In a preferred embodiment theconcrete is poured to a depth of about 6 inches with pipes 30 locatedabout 2 inches below the top surface. In other alternate embodiments ofthe present invention other materials may be used for floor 14 such asbrick, stone and/or wood constructed so as to cover, embed or otherwiseencase pipes 30.

A quantity of fluid 39 is disposed within pipes 30. Fluid 39 may bewater alone, or water mixed with substances such as ethylene glycol andpropylene glycol to promote thermal transfer and prevent freezing of thefluid.

With reference to FIGS. 1, 3 and 4 in combination, a system 40functioning as a heating or cooling element for controlling thetemperature of an open-air environment is shown. System 40 includes atemperature control component 42 for controlling the temperature offluid 39. Temperature control 42 includes a temperature-setting device42 a, such as a conventional bimetal thermostat or electronictemperature control, to establish a control setpoint for a temperatureto be maintained in relation to patio 10. A conventional heat exchanger42 b adds heat to fluid 39 when heating of patio 10 is desired, andremoves heat from the fluid when cooling of the patio is desired. A pump44 for circulating fluid 39 through pipes 30 may include, withoutlimitation, reciprocating, centrifugal and rotary pumps.

In one embodiment, heating fluid 39 to a temperature of about 120° F.results in a temperature of about 105° F. at the surface of floor 14.Heat from the surface of floor 14 will rise, creating a comfortableenvironment within the area established by boundary wall 12 and(optionally) partition 20. Conversely, cooling fluid 39 with heatexchanger 40 b to a temperature less than that of floor 14 will drawheat away from the floor, helping to prevent the build-up of heat onpatio 10 during warm weather.

System 40 may include pipes 30 installed within foundation 22 ofboundary wall 12, in the same manner as described above for floor 14. Insuch embodiments boundary wall 12 preferably supplements the heating andcooling effect of floor 14.

In an alternate embodiment of system 40, other devices may be embeddedin the concrete in addition to or instead of pipes 30, such as electricheating elements (not shown), which may be likewise controlled bytemperature control 42, specifically temperature-setting device 42 a.

Referring now to FIGS. 2 and 5 in combination, to replace or supplementsystem 40 during lower outside ambient temperatures an air deliverysystem 50 provides warm air distributed through a network ofinterconnected ductwork 52 in foundation 22. A temperature-settingdevice 54, such as a conventional bimetal thermostat or temperaturecontrol, may be used to establish a temperature setpoint for atemperature to be maintained in relation to patio 10. A heating orcooling element such as a conventional electric or gas-operated HVACunit 56 heats or cools air drawn from an intake 58. Intake 58 may be afresh-air intake drawing air from outside patio 10, or may recirculateair within patio 10. The temperature-controlled air may optionally bedehumidified by a conventional dehumidifier 60. Movement of air throughair delivery system 50 is accomplished using a conventional air-movingfan or blower 62, the temperature-controlled and dehumidified airpreferably being emitted from diffusers 26 located low in foundation 22proximate floor 14. The warm air will combine with the heat from floor14, resulting in an effective convection heating process. By combiningsystems 40, 50, patio 10 may be made available for use when the outsideambient temperature is as low as about 20° F.

With continued reference to FIG. 5, air delivery system 50 may also beadapted to operate without HVAC unit 56 and/or dehumidifier 60. In thisembodiment system 50 is adapted such that air intake 58 receives heatgenerated by floor 14 and recirculates the heat by circulating it withductwork 52 and communicating the air to the temperature-controlled areathrough a plurality of diffusers 26, providing a convective heatingeffect to patio 10. Fan or blower 62 may or may not be utilized, asdesired.

During warm weather the air delivery system 50 may be used to delivercool air to patio 10. In such conditions the air temperature leaving thediffusers 26 is preferably about 65° F., with a relative humidity ofabout 68%. It is preferable not to deliver colder temperatures, whichmay be perceived by occupants of patio 10 as uncomfortable on bare legs.Colder air temperatures may also cause undesirable condensation in thetemperature-controlled area of patio 10. During high-humidity weather,condensation may be reduced by dehumidifying the cooling air withdehumidifier 60. Dehumidifier 60 may receive air from HVAC unit 56 anddrive the temperature of the air down to about 54° F. Then, using aconventional re-heat process, dehumidifier 60 may raise the temperatureof the air to about 65° F. Mixing in outside air at intake 58 is notpreferred during these conditions, due to the high moisture content ofthe untreated air stream. Re-heating of air within de-humidifier 60 maybe accomplished with a conventional “heat pipe” system or “hot-gasreheat.” Both methods are highly effective and efficient way to raisethe air temperature while maintaining a de-humidified state.

Referring now to FIG. 1 in combination with FIG. 6, during warm weatherit is desirable to minimize the build-up of heat on patio 10 due tosolar radiation 32 from the sun 34. In a preferred embodiment a movablescreen 16 may be located proximate patio 10 to act as a shade byblocking solar radiation 32. Screen 16 may be adapted to move about atrack 18. If desired, the screen may be shaped to complement the themeof the venue. For example, a “spinnaker sail” in keeping with a tropicaltheme for a particular establishment may be appropriately positioned toshade patio 10 from direct sunlight. Screen 16 may be manually movedlaterally about track 18 by hand, and may optionally be manually raised,lowered and tilted as needed to effectively block solar radiation 32.Screen 16 may also be adapted to be manually moved freely in relation topatio 10 and independently of track 18, if desired, such as with awheeled cart or trolley sufficiently constructed to support the screenduring breezy or windy weather conditions. In an alternate embodiment,lateral and elevational movement of screen 16 may be manually butremotely controlled, such as by conventional wired or wireless controlswitches, actuators, relays, motors and the like. Details of theconfiguration of a remote-controlled screen 16 are conventional and areleft to the artisan.

In another alternate embodiment of the present invention, screen 16 maybe automatically actuated by electronic controls wherein appropriatelylocated sensors detect light and/or temperature at points about patio 10and engage actuators and motors to move the screen laterally and/orelevationally to block solar radiation 32 in “hot spots” of bright lightand/or higher temperatures. In a similar embodiment, screen 16 may beautomatically controlled by motors, control switches, relays, actuatorsand the like synchronized to the sun's position in relation to the patioduring various times of the day at any point in the warm-weather season.A predetermined set of instructions, such as a computer program, may beused with a computer, microprocessor, CPU or other conventionalcomputing or control device to accomplish automatic control of screen16. Implementation of manual, remote, and automatic controls areconventional will be apparent to one skilled in the art. As such,details of the implementation manual, remote and automatic controls areleft to the artisan.

Individual shading units, such as umbrellas at each table within patio10, may optionally be used but are not preferred because such shades areless efficient and impinge upon the visual and physical space availablein the patio.

It should be noted that the intent of the heating and cooling systems40, 50 (see FIGS. 4 and 5) is preferably not to control the temperatureof patio 10 to typical interior expectations, but rather to temperambient conditions to a comfortable level. Thus, only as much heating orair conditioning as is required for a comfortable temperature isdesirable to augment the ambient temperature. For example, the optimumtemperature for simulating a tropical setting is about 77° F. to 82° F.Thus, if the temperature is, for example, 50° F., supplemental heat maybe added to patio 10 to achieve the desired temperature.

It is also considered important that heating and cooling systems 40, 50be as inconspicuous as possible so as not to detract from the atmosphereof patio 10. To accomplish this the components of systems 40, 50 arepreferably located remotely, such as within an adjacent building orsuitably disguised in keeping with the decor of patio 10. Diffusers 26are preferably located at a low height and are inconspicuous, preferablymatching or blending in with foundation 22. For example, diffusers 26may simply be narrow slits or openings in stone or brickwork offoundation 22. Air movement should be kept to a velocity that provides acooling breeze during warm weather conditions, yet is not distracting.Noises associated with systems 40 and 50 are preferably kept to aminimum.

Design Calculations

The present invention can be more clearly understood by reference to thefollowing example design calculations. These calculations demonstrateone way to estimate the solar heat load on a patio 10 (see FIG. 1) todetermine a portion of the operating requirements for heating andcooling systems 40, 50. The terms and units of measure associated withthese equations will be familiar to one skilled in the art and thus willnot be discussed. It should be understood that the following examplesare not intended to restrict the scope of the present invention in anymanner.

The total shortwave radiation, I_(t), reaching a surface on earth isgiven by Equation 1:I _(t) =I _(DN)(cos θ)+I _(d) +I _(r)  Equation 1where: I_(DN)=direct normal radiation, θ=angle of incidence betweenincoming solar rays and a line normal to the surface, I_(d)=diffuse skyradiation, and I^(r)=solar radiation reflected from surroundingsurfaces.

On earth's surface on a clear day, I_(DN) is generally represented byEquation 2: $\begin{matrix}{I_{DN} = \frac{A}{\exp\left( \frac{B}{\sin\quad\beta} \right)}} & {{Equation}\quad 2}\end{matrix}$where: A=direct normal radiation, B=atmospheric extinction coefficient,β=solar altitude above a horizontal surface.

For a horizontal surface, cos θ of Equation 1=sin θ of Equation 2.Calculating I_(DN) for example conditions wherein at a particular timeof a particular day at a particular latitude, such as at noon on July 21at 40° N latitude, A=344 BTU/hr-ft², B=0.207, β=70°, sin β=0.939, then$\begin{matrix}{I_{DN} = {\frac{344}{\exp\left( \frac{0.207}{0.939} \right)} = {275\quad{BTU}\text{/}\text{hr}\text{-}{ft}^{2}}}} & {{Equation}\quad 3}\end{matrix}$

The incident solar radiation falling on the horizontal surface, I_(DH),is given by Equation 4:I _(DH) =I _(DN) cos θ=I _(DN) sin β=275 (0.939)=259BTU/hr-ft²  Equation 4

A simplified general relation for the diffuse solar radiation is givenby Equation 5:I _(DS) =CI _(DN) F _(SS) BTU/hr-ft²  Equation 5where: C=diffuse radiation factor, CI_(DN)=sky radiation falling onhorizontal surface, F_(SS)=angle factor between surface is sky (1.0 fora horizontal surface).

If C=0.136 and CI_(DN)=275, then I_(DS) of Equation 5 equals:I _(DS)=(0.136)(275)(1.0)=37.4 BTU/hr-ft²  Equation 6

Assuming I_(r) of Equation 1 is a sufficiently small value that it canbe ignored,I _(t) =I _(DH) =I _(DS)=259+37.4=296.4 BTU/hr-ft²  Equation 7

A heat balance at a sunlit surface has a heat flux, $\frac{q}{A},$given by Equation 8: $\begin{matrix}{\frac{q}{A} = {{\alpha\quad I_{t}} + {h_{0}\left( {t_{0} - t_{s}} \right)} - {ɛ\quad\Delta\quad R}}} & {{Equation}\quad 8}\end{matrix}$where: α=absorptance of the surface for solar radiation, I_(t)=totalsolar radiation incident on the surface, h₀=heat transfer by longwaveradiation and convection at the outer surface, t₀=outdoor airtemperature, t_(s)=surface temperature, ε=hemispherical emittance ofsurface, and ΔR=difference between longwave radiation incident on thesurface from the sky and surroundings, and the radiation emitted by ablackbody at outdoor temperature.

If it is assumed that patio 10 absorbs no heat, then for the net heatflux to be zero, the solar heat load is given by Equation 9:h ₀(t _(s) −t ₀)=αI _(t) −εΔR=solar heat load  Equation 9

For concrete the solar reflectance, ρ, is generally a value of 0.22.Since the absorptance, α=1−ρ, then: α=1−0.22=0.78

For horizontal surfaces exposed to longwave solar radiation from thesky, an appropriate value of ΔR is approximately 20 BTU/hr-ft². Sincethe emissivity, ε, is approximately equal to α for most solids, thesolar heat load is as shown in Equation 10:h ₀(t _(s) −t ₀)=0.78(296.4 BTU/hr-ft²)−0.78(20 BTU/hr-ft²)=215.6BTU/hr-ft²  Equation 10

With reference to FIGS. 7A-7C, the following equations may be used toaid in the design of a floor 14 having a cement pad and an embeddednetwork of interconnected pipes 30: $\begin{matrix}{q^{\prime} = \frac{4\pi\quad{k\left( {T_{1} - T_{2}} \right)}}{\frac{1}{{Bi}_{1}} + {\ln\left\{ {\frac{d}{\pi}r_{1}D} \right){\sinh\left\lbrack {2{\pi\left( {D + \frac{D}{{Bi}_{2}}} \right\rbrack}} \right\}}}}} & {{Equation}\quad 11}\end{matrix}$Where: q′=linear heat flux for each pipe, s=distance between pipecenters, d=pipe depth below the surface, k=the thermal conductivity ofthe solid, r₁=pipe interior diameter, h₁=pipe heat-transfer coefficient,T₁=pipe coolant temperature, h₂=ambient heat-transfer coefficient,$\begin{matrix}{{{Bi}_{1} = {{Biot}\quad{modulus}\quad{for}\quad{the}\quad{pipe}}},} \\{{= \frac{h_{1}r_{1}}{k}},} \\{{Bi}_{2} = {{Biot}\quad{modulus}\quad{for}\quad{exterior}\quad{surface}}} \\{{= \frac{h_{2}d}{k}},} \\{D = {{pipe}\quad{depth}\quad{to}\quad{pitch}\quad{ratio}}} \\{= {\frac{d}{s}.}}\end{matrix}$FIG. 7A illustrates a floor 14 placed atop a thermal insulating material72 and a layer of gravel 74. FIG. 7B illustrates the thermal case forfloor 14 of FIG. 7A, and FIG. 7C illustrates a row of pipes in a wallsuch as foundation 22.

By symmetry, the heat flux through the top surface of floor 14 is onehalf the total heat flux. If the bottom surface of floor 14 is insulatedit is expected that the linear heat flux will be between $\frac{q}{2}$and q. Since both the top and bottom of each pipe 30 can provide heatflow through the top surface of floor 14, Equation 11 can be modified toaccount for this by dividing it by two and multiplying the r₁ term inthe denominator by two, giving Equation 12: $\begin{matrix}{q^{\prime} = \frac{2\pi\quad{k\left( {T_{1} - T_{2}} \right)}}{\frac{1}{{Bi}_{1}} + {\ln\left\{ {\frac{d}{2\pi}r_{1}D} \right){\sinh\left\lbrack {2{\pi\left( {D + \frac{D}{{Bi}_{2}}} \right\rbrack}} \right\}}}}} & {{Equation}\quad 12}\end{matrix}$

To calculate the convective coefficient of pipe 30, assume a surfaceheat flux of $100\quad\frac{BTU}{\text{hr}\text{-}{ft}^{2}}$and a circuit temperature drop, ΔT, of 30° F. The following equationsmay then be applied: $\begin{matrix}{{GPM} = {\frac{\left( {100\frac{BTU}{{hr} - {ft}^{2}}} \right)\left( {3,000\quad{ft}^{2}} \right)}{(30)(500)} = {20\quad{GPM}}}} & {{Equation}\quad 13} \\{Q_{total} = {{20\frac{gal}{\min}\left( \frac{1\quad{ft}^{3}}{8\quad{gal}} \right)} = {2.50\frac{{ft}^{3}}{\min}}}} & {{Equation}\quad 14} \\{Q_{loop} = {\frac{Q_{total}}{18} = {{0.139\frac{{ft}^{3}}{\min}\left( \frac{1\quad\min}{60\quad s} \right)} = {0.0023\frac{{ft}^{3}}{s}}}}} & {{Equation}\quad 15} \\{{Q = {VA}},{V = \frac{Q}{A}},{A = {\frac{\pi\quad D^{2}}{4} = {\frac{{\pi\left( {0.052\quad{ft}} \right)}^{2}}{4} = {0.00212\quad{ft}^{2}}}}}} & {{Equation}\quad 16} \\{V = {\frac{0.0023\frac{{ft}^{3}}{s}}{0.00212\quad{ft}^{2}} = {1.09\quad\frac{ft}{s}}}} & {{Equation}\quad 17} \\{R_{e} = {\frac{\rho\quad u_{m}D}{\mu} = {\frac{\left( {62\frac{lb}{{ft}^{3}}} \right)\left( {1.09\frac{ft}{s}} \right)\left( {0.052\quad{ft}} \right)}{0.000458\frac{{lb}\quad m}{{ft} - s}} = {7,673}}}} & {{Equation}\quad 18} \\{{Nu}_{D} = {{0.023\quad{Re}_{D}^{0.8}\Pr^{0.3}} = \frac{hD}{k}}} & {{Equation}\quad 19} \\{{H_{2}O},{\Pr = 4.53},{k = {0.364\frac{BTU}{{hr} - {ft} - {^\circ}\quad{F.}}}}} & {{Equation}\quad 20} \\{{Nu}_{D} = {{0.023\quad\left( {7,673} \right)^{0.8}(4.53)^{0.3}} = 46.4}} & {{Equation}\quad 21} \\{{Nu}_{D} = \frac{hD}{k}} & {{Equation}\quad 22} \\{h = {\frac{{Nu}_{D}k}{D} = {\frac{46.4\quad(0.364)}{0.052} = {325\frac{BTU}{{{hr} - {ft}} - {{^\circ}\quad{F.}}}}}}} & {{Equation}\quad 23}\end{matrix}$

The following equations and data may be used to calculate the ambientconvective heat transfer coefficient of system 40 (FIG. 4). Assumingheated plates facing upward: Laminar Fluid Flow Turbulent Fluid Flow 104< Gr_(f)Pr_(f) < 109 Gr_(f)Pr_(f) > 109$h = {0.27\left( \frac{\Delta T}{L} \right)^{\frac{1}{4}}}$$h = {0.22({\Delta T})^{\frac{1}{3}}}$

$\begin{matrix}{{{L = {\left( \frac{{Width} + {Length}}{2} \right) = {\frac{\left( {100 + 30} \right)}{2} = {65\quad{ft}}}}}{{{where}\quad L} = {a\quad{vertical}\quad{or}\quad{horizontal}\quad{dimension}\quad{in}\quad{{ft}.}}}}\quad} & {{Equation}\quad 24} \\{h:\frac{BTU}{{hr} - {ft}^{2} - {{^\circ}\quad F}}} & {{Equation}\quad 25} \\{{{\Delta\quad T} = {T_{W} - T_{\infty}}},{{^\circ}\quad F}} & {{Equation}\quad 26} \\{{{Gr}_{f} = \frac{g\quad{\beta\left( {T_{W} - T_{\infty}} \right)}L^{3}}{\upsilon^{2}}},{\Pr_{f} = \frac{\upsilon}{\infty}}} & {{Equation}{\quad\quad}27} \\{{{Gr}_{f}\Pr_{f}} = {{Ra}_{f} = \frac{g\quad{\beta\left( {\Delta\quad T} \right)}L^{3}}{\upsilon\infty}}} & {{Equation}\quad 28} \\{T_{f} = \frac{\left( {T_{W} - T_{\infty}} \right)}{2}} & {{Equation}\quad 29} \\{{{{{Let}:T_{w}} = {100{^\circ}\quad F}},{T_{\infty} = {40{^\circ}\quad F\text{:}}}}{T_{f} = {\frac{\left( {{100{^\circ}\quad F} + {40^{{^\circ}}F}} \right)}{2} = {70^{{^\circ}}F}}}} & {{Equation}{\quad\quad}30} \\{{\frac{g\quad\beta}{\upsilon^{2}} = {2.315 \times 10^{6}\frac{1}{r_{A}{\quad\quad}{ft}^{3}}}},{\Pr = 0.7118}} & {{Equation}\quad 31} \\{{{Ra} = {{\frac{g\quad\beta}{\upsilon^{2}}\left( \Pr \right)\left( L^{3} \right)\left( {\Delta\quad T} \right)} = {{2.315 \times 10^{6}(0.7118)\left( {65{ft}^{3}} \right)\left( {0.60^{{^\circ}}F} \right)} = {2.715 \times 10^{13}}}}}{{{Tubulent}:h} = {{0.22\left( {\Delta\quad T} \right)^{\frac{1}{3}}} = {0.86\frac{BTU}{{hr} - {ft}^{2} -^{{^\circ}}F}}}}} & {{Equation}\quad 32}\end{matrix}$

The surface conductances for air are shown in Table 2, taken from theAmerican Society of Heating, Refrigerating and Air-ConditioningEngineers (“ASHRAE”) “ASHRAE Handbook” (Pub. 2003 by ASHRAE): TABLE 2Surface Emittance Position of Surface Direction of Non-ReflectiveReflective Surface Heat Flow (ε = 0.9) (ε = 0.09) STILL AIR$h_{1}\frac{BTU}{{hr} - {ft}^{2} - {{^\circ}\quad{F.}}}$$h_{1}\frac{BTU}{{hr} - {ft}^{2} - {{^\circ}\quad{F.}}}$ HorizontalUpward 1.63 0.76 MOVING AIR Any (15 mph wind) Any 6.00For masonry, the average surface emittance=0.9

Note that the prior calculation for still air and zero emissivity isroughly equal to the value given here for emissivity=0.05. Therefore,1.63 BTU/hr-ft²° F. will be used for h₂ for still air in order toinclude the effect is of surface emittance. For a 15 mph wind the valueis 6.0 BTU/hr-ft²-° F.

The thermal conductivity of concrete is approximately 0.54 BTU/hr-ft²-°F., as given by the ASHRAE Handbook.

Table 3 contains a summary providing design points for a patio havingthe properties and variables discussed above: TABLE 3 T1 h1 Fluid k h2 sr1 (BTU/hr Temp. d (BTU/ D (BTU/ Bi1 ft ft ft² ° F.) (° F.) (ft)hr-ft-F) (d/s) hr-ft²-F) (h1 r1/k) 0.750 0.024 332 100 0.167 0.54 0.222310000.00 14.70 0.750 0.024 459 106 0.167 0.54 0.2223 10000.00 20.340.750 0.024 577 131 0.167 0.54 0.2223 10000.00 25.57 0.750 0.024 799 1560.167 0.54 0.2223 10000.00 35.40 0.667 0.024 332 120 0.167 0.54 0.25010.86 14.70 0.667 0.024 332 120 0.167 0.54 0.2501 1.60 14.70 0.667 0.024332 120 0.167 0.54 0.2501 6.00 14.70 0.667 0.024 332 130 0.167 0.540.2501 0.86 14.70 0.667 0.024 332 130 0.167 0.54 0.2501 1.60 14.70 0.6670.024 332 130 0.167 0.54 0.2501 6.00 14.70 T2 Td T1′ Ambient Temp T1- q′q″ Surface Qt Bi2 Temp. Drop (Td/2.) (BTU/ (BTU/ Temp Total BTU (h2 d/k)(° F.) (° F.) (° F.) hr-ft) hr-ft²) (° F.) 3000 FT² 3087.04 32 30 8577.64 103.52 32.01 310,549.81 3087.04 32 30 91 87.14 116.18 32.01348,543.92 3087.04 32 30 116 124.60 166.14 32.02 498,412.39 3087.04 3230 141 162.46 216.61 32.02 649,832.63 0.27 40 30 105 26.40 39.60 86.05118,803.20 0.49 40 30 105 39.27 58.90 76.81 176,700.12 1.85 40 30 10567.32 100.98 56.83 302,943.65 0.27 40 30 115 30.46 45.69 93.13137,080.62 0.49 40 30 115 45.31 67.96 82.48 203,884.75 1.85 40 30 11577.68 116.52 59.42 349,550.37

EXAMPLE EMBODIMENT

The present invention can be more clearly understood by reference to thefollowing example embodiment. It should be understood that the followingexample is not intended to restrict the scope of the present inventionin any manner.

Patio 10 (see FIGS. 1-6) may be adapted to simulate an open air,tropical setting. To extend availability with weather conditions incentral Ohio weather, patio 10 is environmentally controlled. A boundaryhaving a stone foundation about three feet high encompasses patio 10,establishing a perimeter. Optically transmissive glass or polycarbonateis mounted atop the foundation, raising the overall height of theboundary to about six feet, effectively creating a conditioned space andacting as a wind break.

Ductwork is embedded within the foundation of the boundary wall. Lowvelocity, long throw diffusers are located along the floor line todisperse conditioned air. The principle works from a “raised floor” HVACdesign concept that conditions the space from the floor rather than theceiling. This puts the emphasis on the “living space,” which is aboutthe first six feet from the floor.

In warm weather the design leaving air temperature from the ductwork isabout 65° F. The air travels along the floor without adversely coolingbare legs. The intent is to temper the extreme days, not to condition tointerior level expectations. Further, an innovative, architecturallyinteresting sun shade is employed. A triangle shaped spinnaker sail froma sail boat is mounted via a three point connection. The sail is placedon rails about 20 feet above the patio along a path that matches thecontour of a rotunda building structure. It moves along the rail,effectively tracking the sun to keep the rays from building a heat loadon the cement below. This allows the patio stay partially shaded andkeep an open feel, unencumbered by umbrellas at every table.

Far more prevalent in central Ohio is cold weather which deters outsidedining. A heater is employed to heat the patio. A concrete floor ispoured with an embedded glycol loop. A dedicated boiler system createsthe hot water necessary for the loop. The heat from the cement radiates,warming the patio space from the floor up. As the heat rises it willcreate a comfortable atmosphere.

When the temperature drops below 40 degrees, warm air will be generatedand dispersed from the diffusers along the boundary wall. Alternatively,system 50 may pick up heat from floor 14 and create a convectiveprocess.

This design allows for a comfortable outdoor experience through anambient temperature range of about 20 to 95° F. The typical patio incentral Ohio is useful for approximately two months out of the year.Accounting for the extreme inclement weather, such as heavy rain orsnow, patio 10 is available for use a cumulative ten months out of theyear.

While this invention has been shown and described with respect todetailed embodiments thereof, it will be understood by those skilled inthe art that various changes in form and detail thereof may be madewithout departing from the scope of the claims of the invention.

1. A system for controlling the temperature of an open-air area,comprising: a boundary wall defining at least a portion of the perimeterof the open-air area to be temperature-controlled; a floor; and aheating or cooling element in the floor, wherein the system is effectiveto control the temperature of the open-air area.
 2. The system of claim1 wherein the heating or cooling element comprises: a network ofinterconnected pipes in the floor; a quantity of fluid disposed withinthe pipes; a heat exchanger for heating or cooling the fluid; and a pumpfor circulating the fluid through the pipes.
 3. The system of claim 1wherein the heating or cooling element comprises a plurality of electricheating elements in the floor.
 4. The system of claim 1, furthercomprising a heating or cooling element in the boundary wall.
 5. Thesystem of claim 1 wherein the boundary wall includes a foundation and anoptically transmissive portion.
 6. The system of claim 1, furtherincluding a movable screen to shade at least a portion of the open-airarea.
 7. The system of claim 6 wherein the screen moves freely inrelation to the open-air area.
 8. The system of claim 6 wherein thescreen moves upon a track.
 9. The system of claim 8 wherein the screenis manually repositioned to maintain shading of the open-air area. 10.The system of claim 9 wherein the screen is manually repositioned with aremote control.
 11. The system of claim 8 wherein the screen isautomatically repositioned to maintain shading of the open-air area. 12.The system of claim 1, further including a partition defining a portionof the perimeter in conjunction with the boundary wall.
 13. The systemof claim 1, further comprising: a network of interconnected ductwork inthe boundary wall; an air intake for receiving air and circulating theair through the ductwork; and a plurality of diffusers in the boundarywall to communicate the air to the open-air area.
 14. A system forcontrolling the temperature of an open-air area, comprising: a boundarywall defining at least a portion of the perimeter of the open-air areato be temperature-controlled; a network of interconnected ductwork inthe boundary wall; a heating or cooling element to heat or cool air; ablower for circulating the heated or cooled air through the ductwork;and a plurality of diffusers in the boundary wall to communicate theheated or cooled air to the open-air area, wherein the system iseffective to control the temperature of the open-air area.
 15. Thesystem of claim 14 wherein the diffusers are inconspicuous.
 16. Thesystem of claim 14, further including a dehumidifier.
 17. The system ofclaim 14 wherein the boundary wall includes a foundation and anoptically transmissive portion.
 18. The system of claim 14, furtherincluding a movable screen to shade at least a portion of the open-airarea.
 19. The system of claim 18 wherein the screen moves freely inrelation to the open-air area.
 20. The system of claim 18 wherein thescreen moves upon a track.
 21. The system of claim 20 wherein the screenis manually repositioned to maintain shading of the open-air area. 22.The system of claim 21 wherein the screen is manually repositioned witha remote control.
 23. The system of claim 18 wherein the screen isautomatically repositioned to maintain shading of the open-air area. 24.A system for controlling the temperature of an open-air area,comprising: a boundary wall defining at least a portion of the perimeterof the open-air area to be temperature-controlled; a floor including: anetwork of interconnected pipes in the floor, and a quantity of fluiddisposed within the pipes; a heat exchanger for heating or cooling thefluid; a pump for circulating the fluid through the pipes; a network ofinterconnected ductwork in the boundary wall; a heating or coolingelement to heat or cool air; a blower for circulating the heated orcooled air through the ductwork; and a plurality of diffusers in theboundary wall to communicate the air to the open-air area, wherein thesystem is effective to control the temperature of the open-air area. 25.The system of claim 24 wherein the boundary wall includes a foundationand an optically transmissive portion.
 26. The system of claim 24,further including a movable screen to shade at least a portion of theopen-air area.
 27. The system of claim 26 wherein the screen movesfreely in relation to the open-air area.
 28. The system of claim 26wherein the screen moves upon a track.
 29. The system of claim 28wherein the screen is manually repositioned to maintain shading of theopen-air area.
 30. The system of claim 29 wherein the screen is manuallyrepositioned with a remote control.
 31. The system of claim 26 whereinthe screen is automatically repositioned to maintain shading of theopen-air area.
 32. A method for controlling the temperature of anopen-air area, comprising the steps of: defining at least a portion ofthe perimeter of the open-air area to be temperature-controlled with aboundary wall; and installing a heating or cooling element in a floor ofthe open-air area, wherein the method is effective to control thetemperature of the open-air area.
 33. The method of claim 32, furthercomprising the steps of: installing a network of interconnected pipes inthe floor; placing a quantity of fluid within the pipes; heating orcooling the fluid; and circulating the fluid through the pipes.
 34. Amethod for controlling the temperature of an open-air area, comprisingthe steps of: defining at least a portion of the perimeter of theopen-air area to be temperature-controlled with a boundary wall;installing a network of interconnected ductwork in the boundary wall;heating or cooling air; circulating the heated or cooled air through theductwork; and communicating the air from the ductwork to the open-airarea, wherein the method is effective to control the temperature of theopen-air area.
 35. A method for controlling the temperature of anopen-air area, comprising the steps of: defining at least a portion ofthe perimeter of the open-air area to be temperature-controlled with aboundary wall; installing a network of interconnected pipes in a floorof the open-air area; placing a quantity of fluid within the pipes;heating or cooling the fluid; circulating the fluid through the pipes;installing a network of interconnected ductwork in the boundary wall;heating or cooling air; circulating the heated or cooled air through theductwork; and communicating the air from the ductwork to the open-airarea, wherein the method is effective to control the temperature of thearea.